When I first came upon my ficus lyrata–the botanical name for the fiddle leaf fig–looking like this, I thought that I had underwatered it and my own neglect was responsible for this ugliness.
But after I watered it–and leaves started falling off–I thought “uh-oh. Something else is going on here.” I actually had to get a hand lens to see the spider mites on it–and they didn’t pass my usual test of “shake the plant over a white piece of paper and study the moving dots.” Nothing was moving but there were clearly mites all over it.
So I took it to the shower for a quick bath of insecticidal soap.
What’s interesting–if you remember my post about the web building spider mites covering the mums in my office–last week this plant was fine. And it’s about 3′ tall–you can see that these are not the leaves of a small plant.
Oh well. It will recover or it won’t. I will just have to watch the other plants around it. I am not sure if snake plants get affected. I suspect not, but you never know.
Gardendaze 
To me, it looks more like it got watered too excessively. Watering more would have exacerbated such a problem. Insects should have caused the developing leaf to become disfigured. How long has it been in this situation? I mean, has it developed new growth since it was moved to this spot? Has it been growing here for a few years? Leaves start out rather odd looking when new, and then mature to match mature leaves.
It’s been in this space and same place 3 years. It had been doing beautifully, which was why when I saw this odd looking leaf (after it looked perfect the week before) I knew I had some sort of issue.
When I pulled the plant out for a closer look, leaves started falling and then I knew I had trouble. These larger leaved ficuses don’t like overwatering–you’re right about that–but they show it by getting black splotches on the leaf margins (been there, done that, as you can tell).
Never a dull moment with the house plants.
Karla